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Biomedical subjects

L Zani

Publications and source records attributed to L Zani.

15 recordsLinked to original sources
PubMed2003

Optimized biogas-fermentation by neural network control.

In this work several feed-forward back-propagation neural networks (FFBP) were trained in order to model, and subsequently control, methane production in anaerobic digesters. To produce data for the training of the neural nets, four anaerobic continuous stirred tank reactors (CSTR) were operated in steady-state conditions at organic loading rates (Br) of about 2 kg x m(-3) x d(-1) chemical oxygen demand (COD), and disturbed by pulse-like increase of the organic loading rate. For the pulses additional carbon sources were added to the basic feed (surplus- and primary sludge) to simulate cofermentation and to increase the COD. Measured parameters were: gas composition, methane production rate, volatile fatty acid concentration, pH, redox potential, volatile suspended solids and COD of feed and effluent. A hierarchical system of neural nets was developed and embedded in a Decision Support System (DSS). A 3-3-1 FFBP simulated the pH with a regression coefficient of 0.82. A 9-3-3 FFBP simulated the volatile fatty acid concentration in the sludge with a regression coefficient of 0.86. And a 9-3-2 FFBP simulated the gas production and gas composition with a regression coefficient of 0.90 and 0.80 respectively. A lab-scale anaerobic CSTR controlled by this tool was able to maintain a methane concentration of about 60% at a rather high gas production rate of between 5 to 5.6 m3 x m(-3) x d(-1).

Calibration↗
PubMed2003

Modelling of the production of gaseous by-products in anaerobic digestion.

Goal of the EU-Project AMONCO (Advanced Prediction, Monitoring and Controlling of Anaerobic Digestion Processes Behaviour towards Biogas Usage in Fuel Cells) is demonstration of the practical use of biogas in fuel cells. The right precondition is a biogas quality which fits into the fuel cells tolerances. Therefore the mission of the workgroup Environmental biotechnology is to control anaerobic digestion in a way that production of potential harmful by-products for fuel cells is reduced. A good understanding of the production of these by products is essential for an applicable decision support tool. This poster presents the modelling of hydrogen sulfide by means of hierarchical neural networks and a classical mathematical method.

Anaerobiosis↗
PubMed2003

A fuzzy logic approach to control anaerobic digestion.

One of the goals of the EU-Project AMONCO (Advanced Prediction, Monitoring and Controlling of Anaerobic Digestion Process Behaviour towards Biogas Usage in Fuel Cells) is to create a control tool for the anaerobic digestion process, which predicts the volumetric organic loading rate (Bv) for the next day, to obtain a high biogas quality and production. The biogas should contain a high methane concentration (over 50%) and a low concentration of components toxic for fuel cells, e.g. hydrogen sulphide, siloxanes, ammonia and mercaptanes. For producing data to test the control tool, four 20 l anaerobic Continuously Stirred Tank Reactors (CSTR) are operated. For controlling two systems were investigated: a pure fuzzy logic system and a hybrid-system which contains a fuzzy based reactor condition calculation and a hierachial neural net in a cascade of optimisation algorithms.

Anaerobiosis↗
PubMed1997

Oxidative metabolism in cultured fibroblasts derived from sporadic Alzheimer's disease (AD) patients.

Fibroblasts from Alzheimer's disease (AD) patients displayed decreased cytochrome c oxidase (complex IV) activity (P < 0.05). The basal oxygen consumption rate (QO2) and the response to an uncoupler of oxidative phosphorylation did not differ between AD and control fibroblasts. The QO2 of AD fibroblasts was more susceptible (P < 0.05) to inhibition by azide in the range 0.5-5 mM. The basal intracellular pH (pHi) in AD fibroblasts was significantly more acidic than in control ones. The results support the hypothesis that subtle dysfunctions of oxidative energy-producing processes are present in fibroblasts from sporadic AD patients. The alterations observed scantly influence the fibroblasts functioning even in stressful conditions; however in tissues, such as the brain, that rely heavily on oxidative metabolism for their function, similar alterations may trigger molecular mechanisms leading to cell damage.

Aged↗
PubMed1987

Sonographic evaluation of the portal venous system after elective endoscopic sclerotherapy of esophageal varices.

In order to evaluate possible changes in the portal venous system after endoscopic sclerosis of esophageal varices, 25 cirrhotic patients underwent abdominal ultrasonography before the first session of sclerotherapy and after eradication of esophageal varices had been achieved. The caliber of the portal, splenic, and superior mesenteric veins was measured sonographically in each case. Sonographic results were compared statistically before and after sclerotherapy. Neither evidence of significant variations in the caliber of the portal veins nor thrombotic obliteration was seen. These results support the view that sclerotherapy has no significant negative side effects on the portal venous system.

Endoscopy↗
PubMed1987

Primary gastric lymphoma versus gastric carcinoma: endoscopic US evaluation.

Endoscopic ultrasonography (US) enables high-resolution imaging of the stomach and can demonstrate the different layers of the gastric wall. It has therefore been proposed for use in evaluating the extension of gastric neoplasms. It was performed in nine patients with primary gastric non-Hodgkin lymphoma and in 36 with gastric carcinoma. The US and pathologic findings were correlated in three surgical specimens of gastric lymphoma. Three different US patterns were found in gastric lymphomas: a polypoid pattern (two cases), localized (two cases) or extended (five cases) hypoechoic infiltration, and thickening with superficial ulcerations. Infiltration was confined to the second and third layers of the gastric wall in six cases and was transmural in three. The study of the gastric lymphoma specimens confirmed the accuracy of US in demonstrating the extent of infiltration. Gastric carcinomas had a more echogenic pattern and a different trend of diffusion, with no extended longitudinal hypoechoic infiltration of the superficial layers or extended hypoechoic transmural infiltration.

Adult↗
PubMed1986

Technique of endoscopic ultrasonography investigation: esophagus, stomach and duodenum.

Endoscopic ultrasonography (EUT) allows a better sonographic image of the internal organs. Moreover, it is possible for the first time to explore the upper GI tract wall. To achieve this, three methods are available: 1) direct apposition of the transducer on the mucosa; 2) contact of a small balloon filled with water over the tip of the ultrasonic probe; 3) direct instillation of water. The esophageal wall is explored with the first and second method; the gastric wall is best explored with the third method; the duodenal wall is explored with the second or the third method. Exploration of esophagus and stomach has been achieved in 100% of cases, duodenal exploration in 72% of cases. No complications occurred in this study.

Duodenoscopy↗
PubMed1986

Detection of portal hypertension and esophageal varices by means of endoscopic ultrasonography.

Endoscopic ultrasonography (EUT) enables not only the visualization of the portal system and of the esophageal varices, as obtained by transabdominal ultrasonography and fiberoptic endoscopy, but also the visualization of intramural and periesophageal collateral veins. Fifteen cirrhotic patients were examined by EUT without complications. When present, esophageal or gastric varices were always detected. In all cases enlarged extrinsic periesophageal veins were visualized, and in 14 of 15 their caliber was correlated with the size of esophageal varices. In three patients examined after sclerotherapy the submucosal veins had disappeared, but extrinsic collateral vessels were patent. EUT will probably become a fundamental technique in the study of portal hypertension and esophageal varices, before and after therapy.

Adult↗
PubMedDate not supplied

Endoscopic ultrasonography in the diagnosis of gastric submucosal tumor.

Endoscopic ultrasonography contributed to a correct diagnosis in 24 of 25 patients with gastric submucosal tumor, including 10 extrinsic compressions and 14 intraparietal growths. Leiomyoma and lipoma were easily recognized. In one case, an unusual group of gastric varices was clearly differentiated from a pedunculated polyp prior to polypectomy. In gastric submucosal tumors, endoscopic ultrasonography can greatly reduce the need for aggressive and risky biopsy techniques or exploratory laparotomy.

Adolescent↗